BEIJING, Jan. 26 (Xinhua) -- The presidents of China and the United States will possibly meet on the sidelines of three international conferences, a former Chinese ambassador to the United States has said.

The meetings could take place on the sidelines of the nuclear security summit in The Hague, Netherlands in March, November's G20 summit in Brisbane, Australia, and the APEC summit in China in autumn, said Zhou Wenzhong, who served as Chinese ambassador to the United States from 2005 to 2010.

Preparations are in full swing for the 2014 APEC Economic Leaders' Meetings in the Chinese capital of Beijing, yet the specific timing has not been announced by the host.

So far neither the Chinese Foreign Ministry nor the U.S. State Department has announced the meeting schedules of the two presidents.

U.S. President Barack Obama has been absent from the APEC summit for the past two consecutive years.

Chinese President Xi Jinping met with Obama twice last year. Apart from their meeting on the sidelines of the G20 summit in Russia in September, they held two-day talks at the Annenberg Retreat at Sunnylands in Rancho Mirage, California in June and reached a consensus on building a new model of China-U.S. relations, which features no conflict, no confrontation, mutual respect, cooperation and common prosperity.

"The 40-odd years of China-U.S. interactions have repeatedly proved that leaders' meetings have been a forceful driver in promoting bilateral relations," said Zhou, now secretary general of the Boao Forum for Asia, citing Richard Nixon's visit to China and Deng Xiaoping's visit to the United States in the 1970s.

More than 90 dialogue and cooperation mechanisms between China and the United States will enable officials, military officers, and scholars of the two countries to meet frequently to seek more cooperation, talk about prominent issues and clear up differences, Zhou said.

The most important mechanism is the annual Strategic and Economic Dialogue (S&ED), which will take place this summer in Beijing, Zhou said. Since its inception in 2009, the S&ED has brought together dozens of influential officials in fields ranging from trade and finance to diplomacy and defense.

Zhou said the two countries will step up bilateral investment treaty(BIT) talks this year.

"Although the United States economy is picking up, it desperately wants China's investment and market. Yet political barriers are preventing Chinese businesses from investing there," Zhou said. "Both sides are highly motivated to sign the BIT."

U.S. investment in China totaled more than 70 billion U.S. dollars, while Chinese investment totaled about 10 billion U.S. dollars, Zhou said, adding that "both countries will benefit a lot if BIT talks succeed."

The BIT is probably the most important trade negotiation since the WTO talks, as it complements both the Trans-Pacific Partnership Agreement and the Transatlantic Trade and Investment Partnership, said Da Wei, a scholar of the China Institutes of Contemporary International Relations.

"I think the BIT talks open new doors for a deeper bilateral economic relationship and would be a good stepping stone to include China in future TPP talks," Da said.

On the military front, the two countries will stage military exercises in disaster relief, fighting piracy and maritime rescue.

"There will be more joint military drills than in 2013," a senior officer of Chinese Defense Ministry Foreign Affairs Office (FAO) said.

Last year, the two militaries conducted two joint exercises in Hawaii and one in the Gulf of Aden.

The Chinese military will play a part in the Rim of the Pacific Exercise(RIMPAC), the officer said on behalf of the FAO but on condition of anonymity.

It is the first time that China has been invited to a U.S-dominated multilateral exercise, the officer said, adding that China has also been invited to the "Golden Cobra" U.S-Thailand military exercise.

U.S. Defense Secretary Chuck Hagel and Chief of Naval Operations Jonathan Greenert are confirmed to visit China, while Chief of the General Staff of the People's Liberation Army Fang Fenghui will visit the United States, the officer said.

However, the FAO officer said there remain three major "obstacles" preventing China-U.S. military ties from going forward. These include arms sales to Taiwan, U.S. naval ships' and aircraft's reconnaissance missions in Chinese waters and airspace, and some bills limiting bilateral military exchanges with China, such as the 2000 Fiscal Year Defense Authorization Act.

The year 2014 coincides with the U.S. midterm election, which will take place on Nov. 4. All 435 seats in the House of Representatives and 33 of the 100 seats in the Senate will be contested along with a great number of state and territorial governorships and state and territorial legislature races.

"During the midterm election year, Obama's attention to China and other foreign affairs will decrease while China topics will be widely discussed in various races, which may partly interfere with China-U.S. ties," said Yuan Peng, deputy head of the China Institutes of Contemporary International Relations.

Long-standing issues in China-U.S. relations, including arms sales to Taiwan and human rights issues, may create new strains on the growth of bilateral ties this year, Yuan said.

With U.S. Ambassador to China Gary Locke's departure around the corner, Obama's nomination of the new U.S. ambassador, Sen. Max Baucus, is awaiting Senate confirmation.